1. Field of the Invention
The present invention relates to a piezoelectric sensor and a detecting device.
2. Description of the Related Art
An exemplary known piezoelectric sensor of the related art which detects bending is a piezoelectric sensor that is described in Japanese Unexamined Patent Application Publication No. 62-156503 described below and that uses the d31 mode.
The piezoelectric sensor described in Japanese Unexamined Patent Application Publication No. 62-156503 has a bimorph structure having a piezoelectric thin film in an upper layer and one in a lower layer. In detection of bending, output from the upper layer and output from the lower layer are measured, and, for example, the output from the upper layer is corrected. Then, the corrected output of the upper layer is added to the output from the lower layer. This enables charge on the upper layer and charge on the lower layer, which are produced due to the pyroelectric effect of the piezoelectric sensor, to cancel each other out.
However, the piezoelectric sensor described in Japanese Unexamined Patent Application Publication No. 62-156503 needs to include a measuring device that measures the output from the upper layer and the output from the lower layer, and a correction circuit that corrects the output from the upper layer or the output from the lower layer, resulting in deterioration in detection efficiency.